Various refractory or ceramic articles are prepared by firing a shaped, green refractory clay at elevated temperatures. Hard refractory balls, such as those used in grinding mills, are commonly prepared in this manner. The balls, or other refractory articles, are piled in saggers which are four-sided boxes having a floor but open at the top. The saggers are also fabricated from fired refractory material such as fire clay.
The present practice of using saggers is laborious and time-consuming. Present techniques often do not take full advantage of the volume of the saggers, resulting in decreased volume of product and waste of heat energy in a kiln. A laborer must manually fill each sagger box with the heavy refractory articles to be fired and then lift and place the sagger box on a kiln car which subsequently carries the sagger into a kiln for firing. Usually a sagger is not completely filled with the refractory articles, resulting in loss of capacity. The laborer must repeat this individual filling, lifting, and placing of each sagger box, normally placing a filled sagger atop another, until a number of saggers are stacked atop each other. There are usually a number of stacks of saggers loaded on a kiln car, each sagger having been manually filled and placed one at a time on the car.
After the car is fired in a kiln and then removed, the procedure must be reversed. The laborer must again take each sagger, heavy with fired product, from its stack and empty its contents. This individual treatment of each sagger is continued until all have been separately unloaded.
In addition, since the saggers are repeatedly subjected to quite high firing temperatures, such as 2650.degree. F, a sagger does not have a long useful life. Sides of a sagger box tend to bow, warp, or crack due to repeated heats. The floors of the saggers are particularly susceptible to this and can become so slumped or otherwise misshapen as to require removal of the sagger from service.